Replacements & Reconstitution in the
Operational ArtofWar

by

1. Introduction

Losses are a fact of military life, whether they
be due to combat (killed, wounded or missing), disease, desertion or, in some
cases and for particular and peculiar reasons, the disbanding of entire units.
Outlined in this document are the distribution mechanisms by which replacements
filter down to understrength units from the inventory pools within the TOAW system.
Note that this is a totally separate process from that of reinforcements, which
can simply be viewed as an extension of a force's Order of Battle entering the
Theatre of Operations on a date later than that at which the scenario starts.

2. Replacement Eligibility

From the manual (italics mine): "Equipment losses are a fact of life on the
battlefield. If these losses are not replaced, your units will become less useful
over time. Your units are eligible to automatically receive replacements from
your force equipment stockpiles if they are under strength, in supply, and not
embarked on ships or trains[i]. In most scenarios, your force replacement
stockpiles will be replenished on a regular basis."

3. Replacement Priority

From the manual (italics mine): "In some scenarios, units may have different
priorities for receiving replacements. This will usually be mentioned in the
scenario briefing". Any unit may have one of the following priorities, as
set in the Scenario Editor by the Designer:

Priority

Percentage Value

None

0 (The Unit NEVER Receives Replacements)

Very Low

20

Low

40

Normal

60

High

80

Very High

100

How these values reflect how many replacements a unit receives is described in
the next section (Replacement Distribution).

4. Replacement Distribution

The results of testing are included in the next two sections, accompanied after that by
supporting logs using TOAW's 'toawlog' and 'uberdude' logging switches (add the following
after the command line for OPART: toawlog uberdude).

Iíve included both a test (OPART) scenario (
ReplacementDistribution+ReconstitutionTest.SCE) and an Excel S/S (
Replacements.XLS) and would urge readers to perform the tests for themselves,
entering the appropriate values in the S/S to compare expected versus actual numbers.
Note that there is ALWAYS an element of variability in the results, reflecting
some randomness within the replacement distribution routines themselves. Readers
might want to vary values to see whether expected #s are still valid- in my experience
they are.

The test scenario concerns results for Side=Germany only (Side=UK is added simply so scenario
will run), using Rifle Squads only[ii] across 6 units with varying Replacement Priorities and
Assigned/Authorized #s. Replacement Rate for Rifle Squads is 5000. Note the testing only
begins turn 2, as this is the first turn replacements are ever issued in any scenario. The
scenario is simply cycled and the results of replacement distribution noted in the S/S turn
by turn. The numbers should be fairly self-explanatory, but indicate (and the logs would tend
to corroborate) that replacement distribution is performed using the following sequence (with
U#[iii] 1 on Turn 2 used as an example here):

Each unit's need is calculated for each item of equipment in its ToE. This is
the difference between assigned and authorized equipment. So assigned and authorized
numbers of 4567 and 9999 Rifle Squads respectively result in a unit need for 5432 Rifle
Squads in our U#1 Turn 2 example.

A pro-rata figure for available replacements as a percentage of total need on any item
of equipment is then calculated. For instance if as on Turn 2 the On Hand and Rate #s for
Rifle Squads in the replacement pool total 5000 and the total need is 31272 the pro-rata
figure used for Rifle Squads is 5000/31272=15.98% which is rounded down to 15%. Note that
units with Replacement Priority=None (i.e. they NEVER receive replacements) have their needs
added to the denominator here (thus having a diluting effect on individual unit requests)
even though they will never actually receive any replacements[iv].

Each unit's replacement request as calculated in (1) is multiplied by the percentage
from (2) to come up with an adjusted individual unit replacement request taking into account
overall item availability. In the U#1 example on Turn 2, this is 5432x0.15=814 Rifle
Squads[v].

Each unit's pro-rated need as calculated in (3) according to item availability is now
pro-rated by its replacement priority- this is in effect what the unit sends in as a
replacement request and is the number units should expect to receive, though there appears
to be a variability of +/-10-15% and non-integer requests appear to be ignored/discarded.
In our example, this would result in a replacement request after all considerations of
814x0.2=162 Rifle Squads- what the unit should expect to approximately receive (in our
example it actually receives 163 Rifle Squads).

Note that in (3) it is possible for the need to be so high across all units, and the requests
from individual units so insignificant as a percentage of the whole need, that when either
step (3) or (4) is calculated, the number returned is a fraction. An example would be a
total need of 10000 with a rate of 100 per turn and a unit requesting individually 50 units
(at 100% priority- so steps (3) and (4) (at 100% priority) produce a request for 50*100/10000
units=0.5 units). In this case, rounding down, the unit will receive nothing. If all units
are in a similar situation on this item of equipment all replacements for the item remain
in the pool and can conceivably be ALL taken by reconstituting units passing the tests for
reconstitution described under section 6.

An extreme example of a scenario exhibiting this behaviour would be Barbarossa 41, where the
Soviet Replacement Rate for Rifle Squads is only 100 per turn, whilst the need, even at
start, is around 17000 spread across a good number of units each of whose needs is no more
than a few 100. In fact it will take a replacement request (authorized less assigned) by a
unit for around 285 Rifle Squads[vi] before it generates (and receives) a pro-rata request for
a single Rifle Squad. Barring no casualties (try it by just cycling through the scenario with
no combat), Rifle Squads may remain in inventory until turn 4 or so, when a unit finally
manages to break the 'integer barrier'. And this is because the replacements have risen
increasing the numerator- from 100/17000 to 400/17000 at which point you need a request for
approximately 285/4 or around only 70 Rifle Squads to actually get a single one.

So in this situation it is much more likely that units will reconstitute before any ever
receive replacements on high overall need items like Rifle Squads here, though this assumes
of course some units are destroyed and are eligible for reconstitution. As units take
casualties and the overall need for Rifle Squads mounts ever higher, the request required
by a unit to gain a single Rifle Squad replacement will rise from 285 to an even higher
number, assuming that replacements cannot be used and go to reconstituting units, resulting
in only the rate for the turn (100) entering the pool each turn. Such is exactly the
situation in Barbarossa 41's early turns- large numbers of Soviet units are heavily damaged
and destroyed, the rate is insufficient to generate more than fractional individual requests
which are therefore not met, resulting in replacements being snapped up by reconstituting
units as fast as they become available and the unit(s) pass(es) the tests for reconstitution.
The process can under certain circumstances feed on itself as the following turn the initial
request by an individual unit needed to generate a final supply depot request for a single
squad after all modifiers will be even higher as the need (denominator) increases- though the
(numerator) rate (all that gets to the pool since on hand has been used for reconstitution in
the prior turn) remains the same.

In similar fashion breaking units down can also make it more difficult for them to receive
replacements, though it will make it easier for them to pass the reconstitution tests. Say
you've got a unit that needs 300 Rifle Squads to get to authorized complement (Step 1).
Assume there are only 100 Rifle Squads as rate per turn and across all units there's a need
for 10,000- so each request for a single squad is translated into a pro-rata request for
100/10000=0.01 squad (Step 2). The unit therefore generates a pro-rata request for 300x0.01=
3 Rifle Squads (Step 3). Replacement priority for all is normal (60%) so a request for 3
Rifle Squads should translate into actually getting 1.8 (Step 4)- that may be either 1 or 2
depending on the random element introduced by the distribution routines. But if the same unit
wanting the same #s was broken down into 3 pieces, each piece would be looking for 1 Rifle
Squad through Step 3. Which translates to expecting 0.6 of what's available in Step 4. It may
get 1 squad but more likely none with the replacements remaining in the pool.

In circumstances like these reconstituting units are the clear winners in getting replacements-
especially since they will take all available on their 'single shot dip' into the replacement
pool as described in Section 6.

6. Reconstitution

From the manual (italics mine): "If your force is at full strength, replacements will
appear in the form of reconstituted previously destroyed units built up from replacement
equipment. Reconstituted units are always "untried". When units are reconstituted there is
a 1 to 4 week delay in their appearance. Reconstituted air units appear at airfields. Other
reconstituted units will appear at a scenario specific point (which should be mentioned in
the scenario briefing) or near friendly supply sources in urban or road locations. If no
friendly supply sources are located in urban or road locations, or if the scenario specific
reentry point is not friendly controlled, land units will not be reconstituted. Special
forces, Coastal artillery, and fixed artillery units are never reconstituted. Reconstituted
airborne and glider units will keep their special icons, but are no longer eligible for
airborne movement. Reconstituted units are listed as such in the Expected Reinforcements
briefing.
The code that decides where to bring reconstituted units back onto the map is quite
intelligent. It will attempt to avoid bottlenecks in unit placements while placing units in
"good" locations. Unless the scenario designer has placed a reconstitution point there,
the chance of a unit appearing at a location isolated by water from the parent formation's
first objective is now very low. Land units will reconstitute in "distant" locations only if
the distant location is specified as the scenario reconstitution point.".

Note that the Scenario Designer can specify within the Scenario Editor that any unit within
a scenario never reconstitutes.
Should there be any destroyed units that can possibly reconstitute, and after replacement
allocation (if any) to on-board units is complete, a check is made to see whether destroyed
units, starting with the unit first in that side's OOB sequence[vii], can pass the reconstitution
criteria, which are:

Any unit attempting to reconstitute needs 66% OR at least 999 units of its full
(authorized) complement of its first line equipment in its ToE listing.

The 999 units may be less than 66% of the total (authorized) complement.

These units must be available from the replacement pool AFTER all on-board units
have received their allotted replacements from whatever replacements remain.

Each unit as it attempts to reconstitute will in turn take as much as it can from
remaining replacements up to a maximum of a full complement for each and every equipment
item in its ToE.

The latter part can be confirmed by looking at the supporting log for Turns 8 and 9.
On turn 8 in the log we can see U#6 being disbanded, so that turn 9 starting replacements
represent the 16793 from turn 8, including the 1 from the disbanded unit, added to the 5000
rate for the turn for a total of 21793- which is what we see. But on turn 9, replacements
are first apportioned out as can be seen, leaving 21014- and indicating replacements are
allocated before any reconstitution attempts are made. The figure of 11015 indicating that
9999 has gone to reconstitute U#6 only shows up at the start of turn 10 and already includes
the new rate (5000), appearing as 16015 'requested replacements available'.

Note that once a unit has taken replacements from the pool and shows as reconstituting, it
takes no more of any equipment item from the pool until it has returned to the map and
begins participating in the regular replacement distribution process. Its supply level also
remains at the same level- i.e. the level it was when the unit was disbanded or destroyed-
until it has returned to the map.

7. Conclusions

It would seem from testing that reconstitution occurs AFTER available replacements
have been distributed to on-board units using any remaining replacements in the pool.

Replacement Distribution occurs in a step-by-step manner- first each unit's need
(authorized less assigned equipment) for each piece of equipment in its ToE is calculated
and the available replacements (rate and on-hand) for this piece of equipment is divided
by the need for it across all units, providing a pro-rata distribution figure (rounded DOWN).
This is then applied to each unit's need to produce a unit request pro-rated by availability.
Lastly this number is pro-rated by each unit's replacement priority to produce an expected
replacement figure per unit. Testing indicates the final distribution per unit may vary
by +/-10-15% and that final non-integer replacement requests are often, though not always
depending on the +/-10-15% variability, ignored.

Testing for Reconstitution occurs AFTER Replacement Distribution for all
destroyed/disbanded units in OOB order. Any off-board (destroyed/disbanded) unit attempting
to reconstitute needs 66% OR at least 999 units of its full (authorized) complement of
its first line equipment in its ToE listing. If a unit finds this minimum number of
replacements available it will reconstitute, taking as many units as are available from the
replacement pool up to its authorized strength for this item of equipment. For other items
of equipment in its ToE, it will take whatever is available or none of the item if none is
available.

8. Design Implications

It is possible for reconstitution to be heavily favoured over replacement distribution,
when the replacement rate is so low as a percentage of the overall need for a particular
item (either as a result of combat or by deliberate scenario design) as to consistently
fail to produce pro-rata integer requests at the individual unit level. Units generating
such fractional replacement requests usually (within the +/-10-15% variability outlined)
receive no replacements.

A warning sign is a low replacement rate (Under 10%) as a percentage of need listed in the
TOAWlog.txt file- if TOAW is run so as to generate this file. Designers might want to
ensure that in such cases the scenario is performing as they would want as regards
Replacement Distribution and, by extension, Reconstitution.

Remedies, should this prove a problem, might include the following:

Changing the rate.

Changing the overall 'need' by reducing the authorized-assigned differential overall
for this equipment item, though it's as well to bear in mind that the overall 'need' is
dependent on a variety of factors and will always be dynamic throughout the scenario.

Changing the Scenario Time Scale. For example if the time scale for a scenario is
weekly and the rate for a particular piece of equipment is 1000 with this generating
fractional per unit replacement requests, changing the time frame to bi-weekly might
allow for a rate of 2000, which in turn might begin to generate integer per unit
replacement requests.

Setting the switch for reconstitution for units to 'No' so they cannot 'soak up'
replacements as described. In which case replacements are more likely to 'stockpile'
if not used to the point where units DO begin to generate integer replacement requests
simply because the numerator in the available/need ratio rises (i.e. available is higher).

Increasing the replacement priority of units so they are less likely to generate
fractional requests.

Eliminating or ensuring there are no or few Replacement Priority=None[viii] units.
These can greatly distort Replacement Distribution since they increase the overall
item 'need' (denominator in available/need ratio) without actually generating any
individual unit Replacement Requests (i.e. they 'dilute' all units Replacement Requests),
reducing the pro-rata number of replacements released for distribution to units. So
should you want to ensure fewer (or no) units remain in the pool post-distribution for
reconstitution you might want to adjust the number of units with Replacement Priority=None
downwards. And obviously their correspondent needs, so that the overall item 'need'
(denominator in available/need ratio) decreases, increasing pro-rata number of
replacements released to units and therefore decreasing units available in the pool
for reconstitution purposes.

Conversely to 6, should you want to ensure units remain in the pool post-distribution
for reconstitution you might want to adjust the number of units with Replacement
Priority=None upwards. And obviously their correspondent needs, so that the overall
item 'need' (denominator in available/need ratio) increases, decreasing pro-rata number
of replacements released to units and therefore increasing units available in the pool
for reconstitution purposes.

Note that the remedies mentioned here may have other effects on play (e.g. changing
Time Scale)- these should also be carefully considered.

9. Play Implications

Players would be wise to note all the above. Additionally, the consequences
of unit breakdowns should also be noted, both as regards the higher probability
of each unit generating a fractional replacement request and therefore getting
none, and as regards the greater likelihood of destroyed/disbanded broken-down
units reconstituting (with a lower 66% of first line equipment threshold)- thereby
soaking up replacements that might otherwise eventually reach on-board units
through the normal Replacement Distribution process.

Players might also want to take care not to have units destroyed early on in
scenarios where there is a large on-hand replacement pool at start that could
cause these units to reconstitute- AND where these replacements might be urgently
needed to compensate for losses in on map units as soon as possible after scenario
start. Otherwise destroyed units may soak up many/all of these replacements
leaving none remaining for on map units when desperately needed- the destroyed
units of course not reappearing on map for up to 4 weeks. This would be especially
true of short time-frame scenarios (1/4 Day Turns) where 4 weeks is represented
by 112 turns- in which case you might never get to see reconstituted units return.

10. Footnotes

iNot stated here, though indicated elsewhere (next section in this document),
is the proviso that the Replacement Priority must be greater than 0%.iiThough the process is equally valid for other equipment items.iiiU#=Unit Number.ivIn this example U#6. This can be tremendously important- with the average replacement
priority having a far greater effect on overall replacement distribution than
any individual unit’s replacement priority, as evidenced in its use in
this equation. Take a unit putting in a request for 100 units when 100 are available
and its priority is Very High (100%). If it were the only unit with a need it
would receive all of them. If another unit with priority=none (i.e. it NEVER
gets replacements) also has a need for 100, the first unit will only receive
50% of its request or (50 units) while the second unit will still get none-
though it has added its ‘need’ to the equation- resulting in 50
units remaining in the replacement pool.vRounding appears to be almost always (brutally) down- judging by the TOAWLog
file.viSoviet Overall Need for Rifle Squads Turn 2=17142. Rate=100. Priority=Normal
(0.6). So 285*(100/17142)*0.6=1.viiThanks to Jarek Flis for coming up with most of these.viiiAgain, this can be tremendously important- with the average replacement priority
having a far greater effect on overall replacement distribution than any individual
unit’s replacement priority, as evidenced in its use in this equation.
And note also there must be a change in need for there to be any impact both
for this remedy and the following (related) one.